A current-mode AMOLED pixel driving circuit directly uses a current signal to drive a pixel circuit. Brightness of an OLED is directly proportional to a value of the driving current, and a multi-level gray scale display can be realized.
As shown in FIG. 1, an existing current-mode AMOLED pixel driving circuit includes a driving transistor TP1, a data writing transistor TP2 and a storage unit; the TP1 and TP2 are PMOS transistors. The storage unit includes a storage capacitor C and a resistor R which are connected in parallel with each other. In a data writing stage, a data-writing control signal Gate received in a gate electrode of the TP2 is of low level, the TP2 turns on, Idata passes through the TP2 and charges the storage capacitor C. In a pixel lighting stage, a light-emitting control signal EM received in a gate electrode of the TP1 is of low level, the TP1 turns on, the storage capacitor C is discharged to light up the OLED. A cathode of the OLED is coupled with a low-level output terminal ELVSS of a driving power supply. The existing current-mode AMOLED pixel driving circuit requires a driving current of a certain value to drive the OLED, and since a charging amount of the storage capacitor in the data writing stage is fixed and the charging amount cannot be adjusted in this stage, thus the gray scale level cannot be adjusted.